<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
#box1{
    width: 200px;
    height: 200px;
    background-color: red;
}
#box2{
    width: 200px;
    height: 200px;
    background-color: yellow;
    /*open relative 盒子相对自身进行定位 偏移量 offset*/
    position: relative;
    /*偏移量*/
    left: 100px;
    top: 150px;
}
#box3{
    width: 200px;
    height: 200px;
    background-color: deepskyblue;
}
    </style>

</head>
<body>


<div id="mian">
    <div id="box1">box1</div>
    <div id="box2">box2</div>
    <div id="box3">box
        <div id="box4">box5</div>
    </div>
</div>


</body>
</html>